Abstract: With the development and utilization of nuclear energy, people pay more and more attention to the impact of discharge water from nuclear power plants on the surrounding ecosystems, and related studies are gradually increasing. We outline the related work of 4 nuclear power plants, including Qinshan, Daya Bay, Ignalina and Almaraz, and summarize the impact of their discharged water on the surrounding ecosystems. It is concluded that the effect of nuclear power plant discharge water on the aquatic ecosystem is mainly affected by the dilution capacity of the water body. When the amount of discharged water is small and the interaction of the receiving water body is strong, the radioactivity level of the surrounding water bodies and organisms will decrease, and the water temperature increase will not be obvious. On the contrary, when the radionuclides in the discharged water are not sufficiently diluted and diffused, the radioactivity level will be significantly higher than the background, and obvious accumulation will occur, and even radiation effects may happen. The water temperature near the discharge port will also rise significantly, resulting in a gradual decrease in the number of constant temperature species of fish and algae. while warm water species become the main body of the community gradually. In addition, with the rapid development of modern computer technology, the use of big data for simulation calculations and selection of model biological experiments for verification will help us better understand the impact of discharged water on aquatic ecosystems, and provide references for nuclear power environmental impact assessment.

Key words: Nuclear power plant, Discharge water, Aquatic organisms, Radionuclide, Water temperature